Heat exchange apparatus for circulating fluidized bed boilers

ABSTRACT

A heat exchange apparatus for circulating fluidized bed boilers is disclosed. The heat exchange apparatus for circulating fluidized bed boilers includes a particle separator configured to separate an exhaust gas and a flow medium discharged from a combustion furnace, an external heat exchanger into which the flow medium collected in the particle separator flows and which is configured to heat a heat transfer medium by heat exchange with the flow medium, and a flow control unit installed at the external heat exchanger and configured to supply air to a flow path of the flow medium and to regulate an internal temperature of the external heat exchanger under the control of a flow direction and a flow quantity of the flow medium.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0092492, filed on Jun. 29, 2015, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a heat exchange apparatus for circulating fluidized bed boilers, and more particularly, to a heat exchange apparatus for circulating fluidized bed boilers capable of controlling a quantity of a flow medium flowing into an external heat exchanger.

2. Discussion of Related Art

Various heat exchangers such as a membrane wall tube provided in a combustion furnace, a wing wall tube provided at an upper portion of the combustion furnace, a platen tube, and the like are applied to a circulating fluidized bed boiler to recover the heat of combustion of coal. However, corrosion of the tube by an exhaust gas and abrasion of the tube by a flow medium may be caused when the tube is disposed on the combustion furnace. Therefore, techniques for installing an external heat exchanger outside the combustion furnace have been developed.

As described above, a conventional circulating fluidized bed boiler including the external heat exchanger has a structure including a combustion furnace, a cyclone, a loop seal, a control valve, and an external heat exchanger. Flow media (grit, ash, etc.) and an exhaust gas in the combustion furnace flow in a cyclone in a mixed state, and are separated into particles having weights greater than or equal to a set weight (hereinafter generally referred to as “flow medium”) and other gases (hereinafter generally referred to as “exhaust gas”) in the cyclone. The exhaust gas separated from the flow medium flows backward through a back pass to be processed, and the flow medium separated from the exhaust gas flows in the loop seal. Then, a portion of the flow medium flows directly into the combustion furnace, and the other portion of the flow medium passes through the external heat exchanger via a control valve and flows into the combustion furnace.

The risk of corrosion of tubes disposed at the external heat exchanger may be resolved since it is possible to avoid direct contact between the tubes and a corrosive exhaust gas, and a temperature of steam in the tubes may be independently controlled since it is possible to adjust a flow rate of the flow medium flowing into the external heat exchanger using the control valve. As the temperature of the steam may be independently controlled as described above, the external heat exchanger is applied so that tubes of a finishing superheater or a finishing reheater of a power generation system are disposed in the external heat exchanger.

However, there are cases in that the flow medium flowing into the external heat exchanger may stay in the control valve, or the control valve may be damaged by the flow medium having a high temperature greater than or equal to 800° C. As a result, the power generation system cannot have a normal output, and an operation of the power generation system may also be stopped when the control valve is seriously damaged. Therefore, costs required to replace, repair and maintain a portion of the control valve may increase.

Also, when the loop seal and the external heat exchanger are separately run, the lack of an available space may be caused, and only one external heat exchanger may be run in one cyclone. As result, there are spatial constraints on an increase in the number of external heat exchangers, that is, an expansion of the external heat exchangers. Therefore, there is a need to improve such a problem.

The background of the present invention is disclosed in Korean Registered Patent No. 10-1352804 (registered on Jan. 13, 2014 and titled “Burning Apparatus and Method for Circulating Fluidized Bed Boiler”).

SUMMARY OF THE INVENTION

The present invention is directed to a heat exchange apparatus for circulating fluidized bed boilers capable of solving unstable operation of a power generation system caused by a control valve and further improving expandability of external heat exchangers.

According to an aspect of the present invention, there is provided a heat exchange apparatus for circulating fluidized bed boilers, which includes a particle separator configured to separate an exhaust gas and a flow medium discharged from a combustion furnace, an external heat exchanger into which the flow medium collected in the particle separator flows and which is configured to heat a heat transfer medium by heat exchange with the flow medium, and a flow control unit installed at the external heat exchanger and configured to supply air to a flow path of the flow medium and to regulate an internal temperature of the external heat exchanger under the control of a flow direction and a flow quantity of the flow medium.

In this case, the external heat exchanger may include a first external heat exchanger connected to the particle separator to communicate therewith. Here, a portion of the flow medium flowing from the particle separator may be heat-exchanged with the heat transfer medium, and the other portion of the flow medium may pass as is.

Also, the first external heat exchanger may include a first housing section, a first inlet section formed at the first housing section to communicate therewith and configured to form a channel into which the flow medium from the particle separator flows, a path chamber formed in the first housing section to communicate with the first inlet section and configured to form a channel extending to the outside of the first housing section, a first heat exchanger inlet chamber which is disposed adjacent to the path chamber and into which the flow medium which does not flow into the path chamber flows, a first heat exchange chamber which is disposed adjacent to the first heat exchanger inlet chamber and in which a first heat exchange tube in which the heat transfer medium flows is installed, and a first outlet section disposed adjacent to the first heat exchange chamber and configured to form a channel through which the flow medium having passed through the first heat exchange chamber is supplied to the combustion furnace.

In addition, the first external heat exchanger may include an inlet compartment wall formed between the path chamber and the first heat exchanger inlet chamber to have an open top portion, a first heat exchanger compartment wall formed between the first heat exchanger inlet chamber and the first heat exchange chamber to have an open bottom portion, and a first outlet compartment wall formed between the first heat exchange chamber and the first outlet section to have an open top portion.

Additionally, the flow control unit may include an inlet control section configured to inject air in a direction across the path chamber and the first heat exchanger inlet chamber, a first supply control section configured to supply air to the first heat exchanger inlet chamber, and a first heat exchange control section configured to inject air in a direction in which the flow medium in the first heat exchange chamber is caused to flow upward.

Further, the inlet control section may include an air injection pipe configured to inject air, and a rotary support unit configured to support the air injection pipe so that an injection direction of the air injection pipe is variable.

Also, the first supply control section may include a first air inlet chamber formed at a lower portion of the first heat exchanger inlet chamber and supplied with external air, and a first air distribution plate configured to compartmentalize the first air inlet chamber and the first heat exchanger inlet chamber and having a plurality of through holes formed therein for allowing the air to pass therethrough.

In addition, the first heat exchange control section may include a second air inlet chamber formed at a lower portion of the first heat exchange chamber and supplied with external air, and a second air distribution plate configured to compartmentalize the second air inlet chamber and the first heat exchange chamber and having a plurality of through holes formed therein for allowing the air to pass therethrough.

Additionally, the first external heat exchanger may include a 1-1^(st) external heat exchanger which is connected to the particle separator to communicate therewith, in which a portion of the flow medium flowing from the particle separator is heat-exchanged with the heat transfer medium and through which the other portion of the flow medium passes as is, and a 1-2^(nd) external heat exchanger which is connected to the 1-1^(st) external heat exchanger to communicate therewith, into which the flow medium having passed through the 1-1^(st) external heat exchanger flows and wherein the flow medium is heat-exchanged with the heat transfer medium.

Also, the external heat exchanger may further include a second external heat exchanger which is installed at the first external heat exchanger to communicate therewith, into which the flow medium having passed through the first external heat exchanger flows and wherein the flow medium is heat-exchanged with the heat transfer medium.

In addition, the second external heat exchanger may include a second housing section, a second inlet section formed between the second housing section and the path chamber to communicate therebetween and configured to form a channel into which the flow medium from the path chamber flows, a second heat exchanger inlet chamber which is formed in the second housing section to communicate with the second inlet section and into which the flow medium having passed through the second inlet section flows, a second heat exchange chamber which is disposed adjacent to the second heat exchanger inlet chamber and in which a second heat exchange tube in which the heat transfer medium flows is installed, and a second outlet section disposed adjacent to the second heat exchange chamber and configured to form a channel through which the flow medium having passed through the second heat exchange chamber is supplied to the combustion furnace.

Additionally, the second external heat exchanger may include a second heat exchanger compartment wall formed between the second heat exchanger inlet chamber and the second heat exchange chamber to have an open bottom portion, and a second outlet compartment wall formed between the second heat exchange chamber and the second outlet section to have an open top portion.

Further, the flow control unit may include a second supply control section configured to supply air to the second heat exchanger inlet chamber, and a second heat exchange control section configured to inject air in a direction in which the flow medium in the second heat exchange chamber is caused to flow upward.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a concept diagram schematically showing a heat exchange apparatus for circulating fluidized bed boilers according to one exemplary embodiment of the present invention;

FIG. 2 is a concept diagram schematically showing an external heat exchanger of the heat exchange apparatus for circulating fluidized bed boilers according to one exemplary embodiment of the present invention;

FIG. 3 is a concept diagram shown to describe an operation of an inlet control section of the heat exchange apparatus for circulating fluidized bed boilers according to one exemplary embodiment of the present invention;

FIG. 4 is a concept diagram schematically showing an external heat exchanger of a heat exchange apparatus for circulating fluidized bed boilers according to another exemplary embodiment of the present invention; and

FIG. 5 is a concept diagram schematically showing an external heat exchanger of a heat exchange apparatus for circulating fluidized bed boilers according to still another exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A heat exchange apparatus for circulating fluidized bed boilers according to one exemplary embodiment of the present invention will be described in detail below with reference to the accompanying drawings. While the present invention is shown and described in connection with exemplary embodiments thereof, it will be apparent to those skilled in the art that various modifications can be made without departing from the scope of the invention.

Unless specifically stated otherwise, all the technical and scientific terms used in this specification have the same meanings as what are generally understood by a person skilled in the related art to which the present invention belongs. In general, the nomenclatures used in this specification and the experimental methods described below are widely known and generally used in the related art.

FIG. 1 is a concept diagram schematically showing a heat exchange apparatus for circulating fluidized bed boilers according to one exemplary embodiment of the present invention, FIG. 2 is a concept diagram schematically showing an external heat exchanger of the heat exchange apparatus for circulating fluidized bed boilers according to one exemplary embodiment of the present invention, and FIG. 3 is a concept diagram shown to describe an operation of an inlet control section of the heat exchange apparatus for circulating fluidized bed boilers according to one exemplary embodiment of the present invention.

FIG. 4 is a concept diagram schematically showing an external heat exchanger of a heat exchange apparatus for circulating fluidized bed boilers according to another exemplary embodiment of the present invention, and FIG. 5 is a concept diagram schematically showing an external heat exchanger of a heat exchange apparatus for circulating fluidized bed boilers according to still another exemplary embodiment of the present invention.

Referring to FIG. 1, a heat exchange apparatus 1 for circulating fluidized bed boilers according to one exemplary embodiment of the present invention includes a particle separator 20, an external heat exchanger 30, and a flow control unit 40.

Constant air flow having a set flow velocity (for example, approximately 2 to 8 m/s) is maintained in a combustion furnace 10 due to the air supplied from a lower portion of the combustion furnace 10, and an exhaust gas and a flow medium are present in a mixed state. The exhaust gas and the flow medium in the combustion furnace 10 are discharged toward the particle separator 20 via an upper portion of the combustion furnace 10. In describing the present invention presented herein, the flow medium refers to particles of grit, ash and the like that flow together with the exhaust gas in a state in which the flow medium is mixed with the exhaust gas.

The particle separator 20 is a device configured to separate the exhaust gas and the flow medium from each other, both of which are discharged from the combustion furnace 10. The exhaust gas and the flow medium are indicated by a gas and particles, respectively, as shown in FIG. 1. When the particle separator 20 can separate and collect the flow medium suspended in the exhaust gas, the particle separator 20 may include a cyclone, an impact-type particle separator, etc. Therefore, a certain structure and shape of the particle separator 20 are not limited.

The external heat exchanger 30 is a device configured to receive the flow medium from the particle separator 20 and wherein the flow medium is heat-exchanged with a heat transfer medium such as water or steam, that is, to heat the heat transfer medium using the flow medium. The external heat exchanger 30 is installed below the particle separator 20 to communicate therewith, and the flow medium settling in the particle separator 20 flows into the external heat exchanger 30 via the lower portion of the particle separator 20.

A cycle is repeated by heating the flow medium to a temperature equal to or higher than a set temperature (for example, 800° C. or more) in the combustion furnace 10, collecting the flow medium in the particle separator 20, and then cooling the flow medium by heat exchanging with the heat transfer medium while passing through the external heat exchanger 30. In this case, the flow medium is caused to continuously circulate through the combustion furnace 10, the particle separator 20, and the external heat exchanger 30.

The flow control unit 40 is a device configured to adjust a flow direction and a flow quantity of the flow medium while supplying and injecting air into a flow path of the flow medium formed in the external heat exchanger 30. The flow control unit 40 is installed to supply and inject air toward a set position of the external heat exchanger 30 in a set direction, and thus adjusts a flow quantity of the flow medium in a certain flow direction by adjusting a flow velocity of the injected air. As such, when the flow of the flow medium is adjusted, an internal temperature of the external heat exchanger 30 may be controlled by adjusting an inflow quantity, a discharge quantity and a remaining amount of the flow medium with respect to the external heat exchanger 30.

Referring to FIGS. 1 and 2, the external heat exchanger 30 according to one exemplary embodiment of the present invention includes a first external heat exchanger 31 and a second external heat exchanger 32.

The first external heat exchanger 31 is connected to the lower portion of the particle separator 20 to communicate therewith. A portion of the flow medium flowing into the first external heat exchanger 31 from the particle separator 20 is heat-exchanged with a heat transfer medium in a first heat exchange tube 315 a installed in the first external heat exchanger 31, and then supplied to the combustion furnace 10, and the other portion of the flow medium flowing into the first external heat exchanger 31 passes through the first external heat exchanger 31 as is, that is, without being heat-exchanged with the heat transfer medium. In describing the present invention, the term “as is” refers to “without being heat-exchanged.”

The second external heat exchanger 32 is installed at and connected to a lower portion of the first external heat exchanger 31 to communicate therewith. The flow medium passing through the first external heat exchanger 31 as is flows into the second external heat exchanger 32, is heat-exchanged with a heat transfer medium in a second heat exchange tube 325 a installed in the second external heat exchanger 32, and then supplied to the combustion furnace 10.

A portion of the flow medium collected in the particle separator 20 is heat-exchanged with the heat transfer medium in the first heat exchange tube 315 a while passing through the first external heat exchanger 31, and the other portion of the flow medium is heat-exchanged with the heat transfer medium in the second heat exchange tube 325 a while passing through the second external heat exchanger 32. That is, the flow medium optionally flows into the first external heat exchanger 31 or the second external heat exchanger 32. In this case, when the air is injected into a channel for a flow medium, which spans from the particle separator 20 to an inner part of the first external heat exchanger 31 and an inner part of the second external heat exchanger 32 to communicate therebetween, using the flow control unit 40, a quantity of the flow medium flowing into the first external heat exchanger 31 or the second external heat exchanger 32 may be adjusted, depending on the velocity and pressure of the injected air.

Referring to FIG. 2, the first external heat exchanger 31 according to one exemplary embodiment of the present invention includes a first housing section 311, a first inlet section 312, a path chamber 313, a first heat exchanger inlet chamber 314, a first heat exchange chamber 315, a first outlet section 316, an inlet compartment wall 317, a first heat exchanger compartment wall 318, and a first outlet compartment wall 319. A flow medium, a heat transfer medium, and fluidizing air used to fluidize the flow medium are indicated by particles, steam and air, respectively, as shown in FIG. 2.

The first housing section 311 has a framework provided as a hollow box shape. The first inlet section 312 is configured to form a channel through which the flow medium flows into an inner part of the first housing section 311 from the particle separator 20, and is formed between the particle separator 20 and the first housing section 311 to communicate therebetween.

The path chamber 313 is configured to form a channel extending from the first inlet section 312 to the outside of the first housing section 311 so that a portion of the flow medium flowing into the first inlet section 312 passes through the first housing section 311 as is. The path chamber 313 is formed in the first housing section 311. Here, the path chamber 313 is formed below the first inlet section 312 to communicate therewith, and formed to extend in a vertical direction.

The first heat exchanger inlet chamber 314 is a space into which a portion of the flow medium that does not flow into the path chamber 313 flows, and is disposed in the first housing section 311 to be adjacent to the path chamber 313. A portion of the flow medium flowing into the first inlet section 312 flows into the first heat exchanger inlet chamber 314, and the other portion of the flow medium flows into the second external heat exchanger 32 via the path chamber 313.

The first heat exchange chamber 315 is a space in which the first heat exchange tube 315 a is installed, and is disposed adjacent to the first heat exchanger inlet chamber 314. The flow medium flowing into the first heat exchanger inlet chamber 314 is heat-exchanged with a heat transfer medium in the first heat exchange tube 315 a while passing through the first heat exchange chamber 315.

The first outlet section 316 is configured to form a channel through which the flow medium passing through the first heat exchange chamber 315 is supplied to the combustion furnace 10 to be circulated. The first outlet section 316 is disposed adjacent to the first heat exchange chamber 315, and formed to extend toward the combustion furnace 10. The flow medium in the first heat exchange chamber 315 is discharged out of the first housing section 311 via the first outlet section 316, and moves through the first outlet section 316 to be supplied to a lower portion of the combustion furnace 10.

The inlet compartment wall 317 is installed between the path chamber 313 and the first heat exchanger inlet chamber 314 to extend in a vertical direction. In this case, the inlet compartment wall 317 is formed to have an open top portion. The first heat exchanger compartment wall 318 is installed between the first heat exchanger inlet chamber 314 and the first heat exchange chamber 315 to extend in a vertical direction. In this case, the first heat exchanger compartment wall 318 is formed to have an open bottom portion. The first outlet compartment wall 319 is installed between the first heat exchange chamber 315 and the first outlet section 316 to extend in a vertical direction. In this case, the first outlet compartment wall 319 is formed to have an open top portion.

In one exemplary embodiment of the present invention as shown in FIG. 2, the first inlet section 312 is formed on an upper right portion of the first housing section 311, and the inlet compartment wall 317 is disposed spaced apart from a right end portion of the first housing section 311. The first heat exchanger compartment wall 318 is disposed to the right of the inlet compartment wall 317 to be spaced apart from the inlet compartment wall 317, and the first outlet compartment wall 319 is formed at a left end portion of the first housing section 311.

The path chamber 313 is formed between the inlet compartment wall 317 and the right end portion of the first housing section 311, and the first heat exchanger inlet chamber 314 is formed between the inlet compartment wall 317 and the first heat exchanger compartment wall 318. Also, the first heat exchange chamber 315 is formed between the first heat exchanger compartment wall 318 and the first outlet compartment wall 319.

According to the configuration as described above, the path chamber 313 and the first heat exchanger inlet chamber 314 are disposed in a shape that diverges below the first inlet section 312. Also, the path chamber 313 and the first heat exchanger inlet chamber 314 are connected through the open top portion of the inlet compartment wall 317 to communicate with each other, the first heat exchanger inlet chamber 314 and the first heat exchange chamber 315 are connected through the open bottom portion of the first heat exchanger compartment wall 318 to communicate with each other, and the first heat exchange chamber 315 and the first outlet section 316 are connected through the open top portion of the first outlet compartment wall 319 to communicate with each other.

Referring to FIG. 2, the second external heat exchanger 32 according to one exemplary embodiment of the present invention includes a second housing section 321, a second inlet section 322, a second heat exchanger inlet chamber 324, a second heat exchange chamber 325, a second outlet section 326, a second heat exchanger compartment wall 328, and a second outlet compartment wall 329, and thus is connected to a lower portion of the first external heat exchanger 31 to communicate therewith.

The second housing section 321, the second inlet section 322, the second heat exchanger inlet chamber 324, the second heat exchange chamber 325, the second outlet section 326, the second heat exchanger compartment wall 328, and the second outlet compartment wall 329 of the second external heat exchanger 32 have structures corresponding, respectively, to the first housing section 311, the first inlet section 312, the first heat exchanger inlet chamber 314, the first heat exchange chamber 315, the first outlet section 316, the first heat exchanger compartment wall 318, and the first outlet compartment wall 319 of the first external heat exchanger 31, and thus detailed descriptions of the overlapping parts will be omitted.

The second inlet section 322 is configured to form a channel through which the flow medium flowing into the path chamber 313 flows into the second housing section 321, and is formed between the second housing section 321 and the path chamber 313 to communicate therewith. The second heat exchanger inlet chamber 324 is a space into which the flow medium passing through the second inlet section 322 flows, and is formed below the second inlet section 322 in an inner part of the second housing section 321.

The second heat exchange chamber 325 is a space in which the second heat exchange tube 325 a is installed, and is disposed adjacent to the second heat exchanger inlet chamber 324. The second outlet section 326 is configured to form a channel through which the flow medium passing through the second heat exchange chamber 325 moves to be supplied to a lower portion of the combustion furnace 10, and is disposed adjacent to the second heat exchange chamber 325.

The second heat exchanger compartment wall 328 is formed between the second heat exchanger inlet chamber 324 and the second heat exchange chamber 325 to have an open bottom portion. The second outlet compartment wall 329 is formed between the second heat exchange chamber 325 and the second outlet section 326 to have an open top portion.

The second heat exchanger inlet chamber 324 and the second heat exchange chamber 325 are connected through the open bottom portion of the second heat exchanger compartment wall 328 to communicate with each other, and the second heat exchange chamber 325 and the second outlet section 326 are connected through the open top portion of the second outlet compartment wall 329 to communicate with each other.

Referring to FIGS. 1 and 2, the flow control unit 40 according to one exemplary embodiment of the present invention includes a first flow control unit 41 and a second flow control unit 42.

The first flow control unit 41 is an air injection system that is installed at the first external heat exchanger 31 to adjust the flow of the flow medium that passes through the first external heat exchanger 31. The second flow control unit 42 is an air injection system that is installed at the second external heat exchanger 32 to adjust the flow of the flow medium that passes through the second external heat exchanger 32.

Referring to FIGS. 2 and 3, the first flow control unit 41 according to one exemplary embodiment of the present invention includes an inlet control section 411, a first supply control section 414, and a first heat exchange control section 417.

The inlet control section 411 injects air through an opening, which is formed at a top portion of the inlet compartment wall 317, in a direction across the path chamber 313 and the first heat exchanger inlet chamber 314. The inlet control section 411 is installed on a right end portion of the first housing section 311 coming in contact with the path chamber 313, and injects air in a leftward direction through the opening formed at the top portion of the inlet compartment wall 317. Referring to FIGS. 2 and 3, the inlet control section 411 according to one exemplary embodiment of the present invention includes an air injection pipe 412 and a rotary support unit 413.

The air injection pipe 412 is a nozzle device configured to supply and inject air into the first housing section 311 in a direction across the path chamber 313 and the first heat exchanger inlet chamber 314. The air injection pipe 412 according to one exemplary embodiment of the present invention is installed on a right end portion of the first housing section 311 coming in contact with the path chamber 313 to face to the left. The air injection pipe 412 may have a multi-pipe structure in which a plurality of pipes are disposed in parallel or disposed coaxially, and an increase and decrease in a flow velocity of air on a plurality of injection paths compartmentalized by the plurality of pipes may be separately controlled.

Referring to FIG. 3, the rotary support unit 413 supports the air injection pipe 412 so that an injection direction of the air injection pipe 412 is variable in a vertical direction. The rotary support unit 413 according to one exemplary embodiment of the present invention has a structure including a hinge shaft configured to pivotally support one end portion of the air injection pipe 412 facing the first housing section 311, a moving shaft coupled to the other end portion of the air injection pipe 412, and an arc-shaped guide unit configured to guide vertical movement of the moving shaft, but the rotary support unit 413 according to one exemplary embodiment of the present invention is not limited thereto. For example, the rotary support unit 413 is not limited to a certain structure and shape when the rotary support unit 413 supports the air injection pipe 412 so that an injection direction of the air injection pipe 412 is variable.

When the rotary support unit 413 is used, a zone of the first heat exchanger compartment wall 318 colliding with the flow medium may expand while variously adjusting an angle of the air injection pipe 412, as shown in FIGS. 3A, 3B and 3C. Therefore, abrasion and damage of the first heat exchanger compartment wall 318 caused by collision with the flow medium may be lowered, compared to when the flow medium is pushed by the air injected through the air injection pipe 412 to exclusively collide with a certain zone of the first heat exchanger compartment wall 318.

In this case, the air injection pipe 412 is connected to the first housing section 311 to communicate therewith via a flexible connecting member 412 a having a flexibly variable length and shape such as a flexible pipe, etc. Therefore, when the angle of the air injection pipe 412 is varied as described above, the air may be stably supplied and injected from the outside of the first housing section 311 to an inner part of the first housing section 311 without any interference with the flow medium.

The first supply control section 414 is a device configured to supply air to the first heat exchanger inlet chamber 314 so that the flow medium can stay suspended in the air in the first heat exchanger inlet chamber 314, that is, the flow medium can be fluidized. Referring to FIG. 2, the first supply control section 414 according to one exemplary embodiment of the present invention includes a first air inlet chamber 415 and a first air distribution plate 416.

The first air inlet chamber 415 is formed below the first heat exchanger inlet chamber 314, and supplied with air from the outside. The first air distribution plate 416 has a plurality of through holes through which the air can pass, and is installed to compartmentalize the first air inlet chamber 415 and the first heat exchanger inlet chamber 314. The first air distribution plate 416 according to one exemplary embodiment of the present invention is obliquely installed toward the first heat exchange chamber 315 to not inhibit a transverse flow of the flow medium that is flowing from the first heat exchanger inlet chamber 314 to the first heat exchange chamber 315.

The air flowing into the first air inlet chamber 415 is uniformly diffused in the first air inlet chamber 415, and then discharged into the first heat exchanger inlet chamber 314 through the plurality of through holes formed in the first air distribution plate 416. Therefore, the air may be supplied at a constant pressure and velocity across a lower portion of the first heat exchanger inlet chamber 314 using the first supply control section 414.

The first heat exchange control section 417 is a device configured to inject air in a direction in which the flow medium in the first heat exchange chamber 315 is caused to flow upward. The flow medium in the first heat exchange chamber 315 is heat-exchanged with a heat transfer medium in the first heat exchange tube 315 a while being caused to flow upward by means of the air injected from the first heat exchange control section 417, and then flows toward the first outlet section 316 through the open top portion of the first outlet compartment wall 319. Referring to FIG. 2, the first heat exchange control section 417 according to one exemplary embodiment of the present invention includes a second air inlet chamber 418 and a second air distribution plate 419.

The second air inlet chamber 418 is formed below the first heat exchange chamber 315, and supplied with air from the outside. The second air distribution plate 419 has a plurality of through holes through which the air can pass, and is installed to compartmentalize the second air inlet chamber 418 and the first heat exchange chamber 315.

The air flowing into the second air inlet chamber 418 is uniformly diffused in the second air inlet chamber 418, and then discharged into the first heat exchange chamber 315 through the plurality of through holes formed in the second air distribution plate 419. Therefore, the air may be supplied at a constant pressure and velocity across a lower portion of the first heat exchange chamber 315 using the first heat exchange control section 417.

Referring to FIG. 2, the second flow control unit 42 according to one exemplary embodiment of the present invention includes a second supply control section 424 and a second heat exchange control section 427, and thus is installed in the second external heat exchanger 32.

The second supply control section 424 and the second heat exchange control section 427 of the second flow control unit 42 have structures corresponding, respectively, to the first supply control section 414 and the first heat exchange control section 417 of the first flow control unit 41, and thus detailed descriptions of the overlapping parts will be omitted.

The second supply control section 424 supplies air to the second heat exchanger inlet chamber 324 to fluidize the flow medium in the second heat exchanger inlet chamber 324. The second heat exchange control section 427 supplies air to a lower portion of the second heat exchange chamber 325 to allow the flow medium in the second heat exchange chamber 325 to flow upward.

In the external heat exchanger 30 having such a configuration according to one exemplary embodiment of the present invention, the first external heat exchanger 31 is compartmentalized into four zones which correspond to the path chamber 313, the first heat exchanger inlet chamber 314, the first heat exchange chamber 315, and the first outlet section 316, and the second external heat exchanger 32 is compartmentalized into three zones which correspond to the second heat exchanger inlet chamber 324, the second heat exchange chamber 325, and the second outlet section 326.

The first external heat exchanger 31 and the second external heat exchanger 32 may be connected through the path chamber 313 to communicate with each other so that the flow medium collected in the particle separator 20 is divided to flow into the first external heat exchanger 31 and the second external heat exchanger 32 at the same time. The high temperature flow medium flowing into the first external heat exchanger 31 is divided by injection air of the inlet control section 411 and moves to the path chamber 313 and the first heat exchanger inlet chamber 314.

The flow medium flowing into the first heat exchanger inlet chamber 314 is fluidized by the air supplied from the first supply control section 414 to move to the first heat exchange chamber 315. In this case, the first heat exchanger inlet chamber 314 serves as a buffer space configured to temporarily store, distribute and buffer the flow medium, that is, serves as a conventional laboratory chamber. Then, the flow medium is heat-exchanged with the heat transfer medium in the first heat exchange tube 315 a using the air injected from the first heat exchange control section 417 disposed at the first heat exchange chamber 315, and then moves to a lower portion of the combustion furnace 10 through the first outlet section 316.

The flow medium flowing into the second heat exchanger inlet chamber 324 of the second external heat exchanger 32 via the path chamber 313 is fluidized by the air supplied from the second supply control section 424 to move to the second heat exchange chamber 325. Then, the flow medium is heat-exchanged with the heat transfer medium in the second heat exchange tube 325 a using the air injected from the second heat exchange control section 427 disposed at the second heat exchange chamber 325, and then moves to a lower portion of the combustion furnace 10 through the second outlet section 326.

As described above, the quantity of the flow medium flowing into the first external heat exchanger 31 and the second external heat exchanger 32 is related to the velocity (flow rate) of the air injected from the inlet control section 411, the first heat exchange control section 417, and the second heat exchange control section 427, as can be seen from the following tables. Therefore, the quantity, particularly, a relative flow rate (hereinafter referred to as a “flow medium proportion”) of the flow medium flowing into the first external heat exchanger 31 and the second external heat exchanger 32 may be adjusted by adjusting the velocity of the air injected from the inlet control section 411, the first heat exchange control section 417, and the second heat exchange control section 427.

The following tables summarize experimental results performed at room temperature under the conditions that the path chamber 313, the first heat exchanger inlet chamber 314, the first heat exchange chamber 315 and the first outlet section 316 of the first external heat exchanger 31 are present at a transverse width ratio of 1:2:3:1 and the first housing section 311 is present at a vertical width ratio corresponding to 5. Also, the following tables summarize experimental results performed at room temperature under the conditions that the second heat exchanger inlet chamber 324, the second heat exchange chamber 325 and the second outlet section 326 of the second external heat exchanger 32 are present at a transverse width ratio of 2:4:1 and the second housing section 321 is present at a vertical width ratio corresponding to 5. To check an effect of individual parameters, one parameter is adjusted while the other parameters are fixed, and the quantity of the flow medium is indicated by a proportion of the flow medium flowing into the first external heat exchanger 31 and the second external heat exchanger 32.

TABLE 1 Flow medium proportion Injection velocity (m/s) First heat Second heat of inlet control section exchanger exchanger 2 0.19 0.81 4 0.22 0.78 6 0.3 0.7 8 0.42 0.58

TABLE 2 Injection velocity (m/s) Flow medium proportion of first heat exchange First heat Second heat control section exchanger exchanger 0.3 0.2 0.8 0.5 0.4 0.6 0.7 0.7 0.3 0.9 0.85 0.15

TABLE 3 Injection velocity (m/s) Flow medium proportion of second heat exchange First heat Second heat control section exchanger exchanger 0.3 0.4 0.6 0.5 0.2 0.8 0.7 0.15 0.85 0.9 0.05 0.95

From the tables, it can be seen that the quantity of the flow medium flowing into the first external heat exchanger 31 and the second external heat exchanger 32 is adjustable when the velocity of the air supplied and injected from the flow control unit 40 was adjusted. That is, it can be seen that, when the velocity of the air supplied and injected from the flow control unit 40 is adjusted, the quantity of the flow medium flowing into the first external heat exchanger 31 and the second external heat exchanger 32 is adjustable without using a separate valve unit corresponding to the control valve installed with the conventional loop seal, the heat absorption quantity of the heat transfer medium passing through the first external heat exchanger 31 and the second external heat exchanger 32 is adjustable to a target value, and the final temperature of the heat transfer medium flowing into a turbine of a power generation system is controllable.

Since the heat transfer medium in the first heat exchange tube 315 a and the second heat exchange tube 325 a is able to be heated to a higher temperature at a higher pressure as a larger quantity of the flow medium is flowed into the first external heat exchanger 31 and the second external heat exchanger 32, the proportion of the flow medium flowing into the first external heat exchanger 31 and the second external heat exchanger 32 is able to be adjusted by adjusting the velocity of the air injected from the inlet control section 411, the first heat exchange control section 417 and the second heat exchange control section 427. Also, the first heat exchange tube 315 a and the second heat exchange tube 325 a may be divided and optionally applied as an evaporator, a superheater, a reheater, or the like, depending on their heat absorption quantities.

Also, a heat absorption area of each of the evaporator, the superheater and the reheater varies depending on whether a subcritical pressure or a supercritical pressure is applied to a boiler. According to the present invention, the heat absorption quantity of each of the evaporator, the superheater and the reheater can be easily varied when necessary, without any inconvenience of adjusting the heat absorption area of each of the evaporator, the superheater and the reheater, by adjusting the quantity of the flow medium flowing into the first external heat exchanger 31 and the second external heat exchanger 32, as described above.

Referring to FIG. 4, the external heat exchanger 30 according to another exemplary embodiment of the present invention has a structure of the first external heat exchanger 31 including a 1-1^(st) external heat exchanger 31A and a 1-2^(nd) external heat exchanger 31B.

The 1-1^(st) external heat exchanger 31A has the same structure as the first external heat exchanger 31 according to one exemplary embodiment of the present invention as shown in FIG. 2. The 1-1^(st) external heat exchanger 31A is connected to the particle separator 20 to communicate therewith, and a portion of the flow medium flowing from the particle separator 20 is heat-exchanged with a heat transfer medium, and the other portion of the flow medium passes through the path chamber 313 as is.

The 1-2^(nd) external heat exchanger 31B has the same structure as the 1-1^(st) external heat exchanger 31A. In this case, the 1-2^(nd) external heat exchanger 31B is serially connected to a lower portion of the 1-1^(st) external heat exchanger 31A, and the second external heat exchanger 32 is serially connected to a lower portion of the 1-2^(nd) external heat exchanger 31B. The 1-2^(nd) external heat exchanger 31B is connected to the 1-1^(st) external heat exchanger 31A to communicate therewith, and the flow medium passing through the 1-1^(st) external heat exchanger 31A as is flows into the 1-2^(nd) external heat exchanger 31B. In this case, a portion of the flow medium flowing into the 1-2^(nd) external heat exchanger 31B is heat-exchanged with a heat transfer medium, and the other portion of the flow medium passes toward the second external heat exchanger 32 as is.

In accordance with the external heat exchanger 30 according to one exemplary embodiment of the present invention, the plurality of external heat exchangers corresponding to the first external heat exchanger 31 and the second external heat exchanger 32 may be connected to be controlled with respect to one particle separator 20, thereby further improving expandability of the external heat exchanger. Also, when three or more external heat exchangers 30 are required, the plurality of first external heat exchangers 31 may be serially connected in a vertical direction according to another exemplary embodiment of the present invention as shown in FIG. 4, thereby further improving the expandability of the external heat exchanger.

Also, the present invention is not limited to only a case in which the plurality of external heat exchangers 30 can be applied when the flow of the flow medium can be controlled while supplying and injecting air onto a flow path of the flow medium. As shown in FIG. 5, the heat exchange apparatus can be effectively used even when only one external heat exchanger 30 corresponding to the first external heat exchanger 31 is applied.

In accordance with the heat exchange apparatus 1 for circulating fluidized bed boilers having such a configuration according to the present invention, fluidizing air used to fluidize the flow medium may be supplied to the flow path of the flow medium using the flow control unit 40, and the inner temperature of the external heat exchanger 30 may be regulated under the control of a flow direction and a flow quantity of the flow medium.

Also, according to the present invention, since a steam temperature of the heat transfer medium passing through each of the plurality of external heat exchangers 30 may be freely regulated by adjusting the quantity of the flow medium flowing into each of the plurality of external heat exchangers 30, the power generation system may be operated more stably.

In addition, according to the present invention, prior-art problems such as rejections and stoppages in the power generation system caused by clogging and damage of the conventional control valve may be solved, and thus the power generation system may be operated more stably, and maintenance and management costs may be reduced, compared to the conventional heat exchange apparatuses requiring excessive costs to replace, repair and maintain the control valve.

Further, according to the present invention, since the heat exchange apparatus has a loop seal-integrated structure in which the external heat exchanger 30 is formed integrally with a conventional loop seal, the heat exchange apparatus may utilize space more efficiently, compared to the conventional heat exchange apparatuses including a separate loop seal, and two or more external heat exchangers 30 may be run with respect to one particle separator 20. When necessary, the heat exchange apparatus may be applied to or combined with an evaporator, a superheater, a reheater, and the like, thereby further improving an expansion in the number and functions of the external heat exchangers 30.

In accordance with the heat exchange apparatus for circulating fluidized bed boilers according to the present invention, fluidizing air used to fluidize the flow medium can be supplied to the flow path of the flow medium using the flow control unit, and the inner temperature of the external heat exchanger can be regulated under the control of a flow direction and a flow quantity of the flow medium.

Also, according to the present invention, since a steam temperature of the heat transfer medium passing through each of the plurality of external heat exchangers can be freely regulated by adjusting the quantity of the flow medium flowing in each of the plurality of external heat exchangers, the power generation system can be operated more stably.

In addition, according to the present invention, prior-art problems such as rejections and stoppages in the power generation system caused by clogging and damage of the conventional control valve can be solved, and thus the power generation system can be operated more stably, and maintenance and management costs can be reduced, compared to the conventional heat exchange apparatuses requiring excessive costs to replace, repair and maintain the control valve.

Further, according to the present invention, since the heat exchange apparatus has a loop seal-integrated structure in which the external heat exchanger is formed integrally with a conventional loop seal, the heat exchange apparatus can utilize space more efficiently, compared to the conventional heat exchange apparatuses including a separate loop seal, and two or more external heat exchangers can be run with respect to one particle separator. When necessary, the heat exchange apparatus can be applied to or combined with an evaporator, a superheater, a reheater, and the like, thereby further improving an expansion in the number and functions of the external heat exchangers.

It will be apparent to those skilled in the art that various modifications can be made to the above-described exemplary embodiments of the present invention without departing from the scope of the invention. Thus, it is intended that the present invention covers all such modifications provided they come within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. A heat exchange apparatus for circulating fluidized bed boiler, comprising: a particle separator configured to separate an exhaust gas and a flow medium discharged from a combustion furnace; an external heat exchanger into which the flow medium collected in the particle separator flows and which is configured to heat a heat transfer medium by heat exchange with the flow medium; and a flow control unit installed at the external heat exchanger and configured to supply air to a flow path of the flow medium and to regulate an internal temperature of the external heat exchanger under the control of a flow direction and a flow quantity of the flow medium.
 2. The heat exchange apparatus of claim 1, wherein the external heat exchanger comprises a first external heat exchanger connected to the particle separator to communicate therewith, wherein a portion of the flow medium flowing from the particle separator is heat-exchanged with the heat transfer medium, and the other portion of the flow medium passes as is.
 3. The heat exchange apparatus of claim 2, wherein the first external heat exchanger comprises: a first housing section; a first inlet section formed at the first housing section to communicate therewith and configured to form a channel into which the flow medium from the particle separator flows; a path chamber formed in the first housing section to communicate with the first inlet section and configured to form a channel extending to the outside of the first housing section; a first heat exchanger inlet chamber which is disposed adjacent to the path chamber and into which the flow medium which does not flow into the path chamber flows; a first heat exchange chamber which is disposed adjacent to the first heat exchanger inlet chamber and in which a first heat exchange tube in which the heat transfer medium flows is installed; and a first outlet section disposed adjacent to the first heat exchange chamber and configured to form a channel through which the flow medium having passed through the first heat exchange chamber is supplied to the combustion furnace.
 4. The heat exchange apparatus of claim 3, wherein the first external heat exchanger comprises: an inlet compartment wall formed between the path chamber and the first heat exchanger inlet chamber to have an open top portion; a first heat exchanger compartment wall formed between the first heat exchanger inlet chamber and the first heat exchange chamber to have an open bottom portion; and a first outlet compartment wall formed between the first heat exchange chamber and the first outlet section to have an open top portion.
 5. The heat exchange apparatus of claim 3, wherein the flow control unit comprises: an inlet control section configured to inject air in a direction across the path chamber and the first heat exchanger inlet chamber; a first supply control section configured to supply air to the first heat exchanger inlet chamber; and a first heat exchange control section configured to inject air in a direction in which the flow medium in the first heat exchange chamber is caused to flow upward.
 6. The heat exchange apparatus of claim 5, wherein the inlet control section comprises: an air injection pipe configured to inject air; and a rotary support unit configured to support the air injection pipe so that an injection direction of the air injection pipe is variable.
 7. The heat exchange apparatus of claim 5, wherein the first supply control section comprises: a first air inlet chamber formed at a lower portion of the first heat exchanger inlet chamber and supplied with external air; and a first air distribution plate configured to compartmentalize the first air inlet chamber and the first heat exchanger inlet chamber and having a plurality of through holes formed therein for the air to pass therethrough.
 8. The heat exchange apparatus of claim 5, wherein the first heat exchange control section comprises: a second air inlet chamber formed at a lower portion of the first heat exchange chamber and supplied with external air; and a second air distribution plate configured to compartmentalize the second air inlet chamber and the first heat exchange chamber and having a plurality of through holes formed therein for the air to pass therethrough.
 9. The heat exchange apparatus of claim 2, wherein the first external heat exchanger comprises: a 1-1^(st) external heat exchanger which is connected to the particle separator to communicate therewith, in which a portion of the flow medium flowing from the particle separator is heat-exchanged with the heat transfer medium and through which the other portion of the flow medium passes as is; and a 1-2^(nd) external heat exchanger which is connected to the 1-1^(st) external heat exchanger to communicate therewith, into which the flow medium having passed through the 1-1^(st) external heat exchanger flows and wherein the flow medium is heat-exchanged with the heat transfer medium.
 10. The heat exchange apparatus of claim 2, wherein the external heat exchanger further comprises: a second external heat exchanger which is installed at the first external heat exchanger to communicate therewith, into which the flow medium having passed through the first external heat exchanger flows and wherein the flow medium is heat-exchanged with the heat transfer medium.
 11. The heat exchange apparatus of claim 10, wherein the second external heat exchanger comprises: a second housing section; a second inlet section formed between the second housing section and the path chamber to communicate therebetween and configured to form a channel into which the flow medium from the path chamber flows; a second heat exchanger inlet chamber which is formed in the second housing section to communicate with the second inlet section and into which the flow medium having passed through the second inlet section flows; a second heat exchange chamber which is disposed adjacent to the second heat exchanger inlet chamber and in which a second heat exchange tube in which the heat transfer medium flows is installed; and a second outlet section disposed adjacent to the second heat exchange chamber and configured to form a channel through which the flow medium having passed through the second heat exchange chamber is supplied to the combustion furnace.
 12. The heat exchange apparatus of claim 11, wherein the second external heat exchanger comprises: a second heat exchanger compartment wall formed between the second heat exchanger inlet chamber and the second heat exchange chamber to have an open bottom portion; and a second outlet compartment wall formed between the second heat exchange chamber and the second outlet section to have an open top portion.
 13. The heat exchange apparatus of claim 11, wherein the flow control unit comprises: a second supply control section configured to supply air to the second heat exchanger inlet chamber; and a second heat exchange control section configured to inject air in a direction in which the flow medium in the second heat exchange chamber is caused to flow upward. 